If fish will eat butterflies, then how about moths. I know if I leave my porchlight on at night every moth in the neighborhood stops by to say "Hi" In a few minutes you will have a handful of tasty treats.
Slappy, Maybe Albinos or ADFs......hmmm......moths and flies will be next on the hit list, maybe lightning bugs too......those three are pretty abundant around here.
I also forgot....about a week ago I fed him a baby perch that I caught, I was worried about bacteria\disease, but all is well so far, maybe next time I go I will feed him a blue gill if I can catch one
u live in japan???? awesome! and try lightning bugs, earwigs, or small strips of chicken meat. and what kinda fish is this again? no letters, a FULL NAME.